The present invention relates to a transformer including a frame type iron core having plate-shaped magnetic members laminated in the order based on the widths of the plate-shaped magnetic members, wherein the magnetic members form respective annular magnetic circuits. The invention more particularly relates to the configuration of the frame type iron core.
According to the amendment of the Law concerning the Rational Use of Energy, the law concerning improvement of characteristics of transformers has come into effect from April, 2006. To comply with the law concerning improvement of characteristics of transformers, it is necessary to reduce loss (no-load loss) that may occur at iron cores included in transformers. In order to reduce a no-load loss of a frame type iron core including laminated plate-shaped magnetic members having different widths, the following measures have been taken so far. In the first one of the measures, magnetic members having excellent magnetic properties are used as the plate-shaped magnetic members forming the frame type iron core. In the second one, joint portions, each of which is formed by joining together end surfaces of the plate-shaped magnetic members, are shifted from each other in the direction of a magnetic path. In the third one, the number of the laminated plate-shaped magnetic members is increased.